Method of plugging a well bore with a thermosetting resin



Fel 23, 1965 w. E. HOLLAND ETAL METHOD OF PLUGGIING A WELL BORE WITH A THERMOSETTING RESIN Filed June 25, 1962 DUMP BAILER EPOXY RESIN II R. w Mlnwnwlw y v.. Ls E NYY E LL V T. EE ALS NALS N TA SG L R B 0U ELRD E LL5 V ON o M PP OC.I T. X NH L T E .l .Rw A E C S NEM ELA RRI RAM AHl WCW N .S V. E B RII l s M L L m A9 E B il. .lillllllllll .nlvl!!llIIIlllnllllllllllllllflllIfiilllllllllIit4lflllrllllllllllllllltv..IIIIIIII DUMP BAILER cementitious material.

Scott, at page 141 of the United States Patent O 3,170,516 METHOD OF PLUGGING A WELL EURE WITH y A THERMOSETTING RESIN Warren E. Holland and Charles B. Corley, dr., Houston, and William C. Lindsey, Corpus Christi, Tex., assignors, by mesne assignments, to Jersey Production lResearch Company, Tulsa, Okla., a corporation of Delaware Filed June 25, 1962, Ser. No. 204,700

Claims. l (Cl. 166-23) produce the formation by natural ow. l Pumping equipment may be yeffectively used for a period of time to 'produce tluids from theformation, but eventually the formation `will become so depleted. that further production is unec'onomical. vOtherfactors than pressure maintenance, such as Water intrusion into the well bore, may enterl into the decisionto no longer produce the formation. On-gccasio'n it may be' found feasible to produce hydrocarbons from a second earth stratum that intersects the well bore at a higher level than the iirst earth stratum. It then becomes desirable to'v isolate the two strata so vthat the iirststr-atumvwill vnot be produced simultaneously y with thel second stratum.4 `It has been customary inthe pastto isolatestratabymeans of strong, heavy bridge plugs, the setting of which requires that the production conduit, or flow tubing string, be pulled from the well.

- Recently, there have become available drillable bridge plugs that maybe run through tubing strings on a wire line. VThe use of such apparatus isy desirable because the placementthereof is not expensive anddoes not require recompletion rigs at the earths surface for pull- I'ing tubing and similarA operations. vFurthermore, the Vplugs are particularly adapted foruse in wells which have beenpreviously set up for permanent-type. comple-y vtion work.V` These: particular bridge plugs kall make use of a rather fragile stopfdevice that may be expanded to the interio'rfof the casing stringv after having been run out ofthe Ilower end of the tubing string. .When the bridge plug has been set at the desired location in a casing string, a quantity of cement isdumped on top of the stop device `and allowed to set.' Usually abquantity of .pea gravel Aand sand is dumped ahead of the cement to provide a suitable support plug or base for'the uid Through-tubing bridge plugs are described in some detail in an article entitled How Through-Tubing VBridgellugs Work, by Robert W.

October `1959 issue of the periodical World Oil. *I Y Itis-.manifest that a large differential `pressure will be exented across the set plug inasmuch as the second upper productive formation will have a much higher formation willbecome'loosened asfthe result of the differential pressure thereacross and Awill move downwardly so Ithat the: Y .ftwo earth. ystrata arel brought into fluid'-communicatiun.Il

vhydes.

tion resins, types that have particularly desirable wettingl 3,170,516' Patented Feb. 23, 1&65

The differential pressure that may be exerted across a bridge plug without the bridge plug becoming loosened will be dependent upon the extent to which the cementitious mixture wets @and adheres to the inner surface of the casing and on the area of adhesion. Substitution of a duid material, other than cement, that has better wetting and adhering properties manifestly would result in a more desirable bridge plug. In recent years a number of such materials have become available which have been termed thermosetting phenolic condensation resins. Examples of such thermosetting phenolic condensation resins are the condensation products of phenol-ic bodies with reactive bodies, such as epichlorhydrin, also called 1 chloro-2,3-epoxypropane, and various amines and alde- Other types of thermosetting phenolic condensaand adhering properties, are epoxy resins, which are diglycidyl ethers of polyalcohols or polyphenols such as the product obtained by the reaction between epichlorohydrin and bisphenol A using carefully controlled additions of caustic soda to control the pH by neutralizing the hydrochloric acid formedin the reaction. The pH is maintained below Ithe end point of phenolphthalein, about Sto 8.5. ABisphenol Ais 'sometimes referred to as 2,Z-n-propylidparaphenol. The vepoxy p resins formed from bisphenol A. have atleast two reactiveepoxy gro-ups in their molecule and are representedby .the 'formular where n is an integer having a value of 1 or a greater number, and are preferred in connection with the present invention. It is usual to use catalytic curing agents known as hardeners oraccelerators with the thermos/etting resin lto catalyze the hardening reaction of the resins at low temperatures. Y f

While the use of. such thermosetting condensation resins would appear to give ybetter results in the formation of bridge plugs than would ordinary iiuid cement, it has been found that usually such is not the case, particularly when such plugs are set in casings having a diameter greater than about 3 inches. Bridge plugs formed by dumping thermosetting condensation` resins and hardeners therefor on a4 supportplug will be found to be characterized by -very lowV strength; such pings 'fail at small d-iiferential pressures thereacrcss.

, It now has been found, however, that extremely strong bridge plugs may be .formed by setting a support plug kin a casing in accordance with the prior art, and deposit- I pressure than the first, depleted lower formation. :It has been foundthatsuch through-tubing bridge plugs often g ing thereon a quantity of Aa mixture of athermosetting condensation resin anda catalytic hardener `therefor, along` Y diameter of the dump bailer in order to prevent bridging of vthe balls in the bailer..l In depositingthe resin and hardener, it has been found that the Strength'of the bond y may be unexpectedly enhanced by keeping the deposition port ofthe; bailer below the surface ofthe fluid resinhardener mixture insofar asis possible.

Objects and'features of the invention that. are not appar-' 4 entV from the above description will becomeevident upon vconsideration of thefollowing detailed descriptiontbereof resin having a viscosityless than 5000. cps.

Y hardener mixturel 11.

when taken in connection with the yaccompanying drawing, wherein: f

FIG. l is a vertical cross-sectional view, partially in elevation, of a dump Ybailer that may be used in connection with theinvention;v yand FIGS. 2 and 3 are schematic representations of an oil well installation illustrating two of the steps of the..`

method of the invention. y f

With reference now to l"lG.i1, there is illustrated a through-tubing dump bailer suitable for use with the invention. The bailer comprises a housing 1 having a filling window or port Sarthe upper .end thereof, and a deposition port at the lower `end ,thereof which is illustrated as being sealed by an explosive plug 5 The explosive plug preferably is'of the type that is electricallyidetonated by electrical current from the earths surface. Preferably, the entirel lowerend of the housing l is opened upon detonation of the explosive plug 5 such that the lower end. Y* of the housing Ail may be considered as'the deposition port` of the bailer. Electricalcurrent for detonation of the plug may be derivedfrom an electrical source (not shownyat the-earths surface' to which the plugis connected by au electrical conductor onV cable 7.5 Withinv the housing 'l are a plurality of-metallic balls 9 r anda mixture 11 of a thermosetting condensation resin and acatalytc hardener' therefor to acceleratethe hardening process.,

As indicated above, the` preferred thermosetting -condensation resinis m epoxy resin', and preferably an-epoxy epoxy resin is used, the curing or'hardening of .the resin maybeaccelerated in any of the followingman'ner's (l) direct linkage between the epoxide groupsV by the usey of tertiary amines of the general formula'RSNg (Bf-linkage termtdi'silarl'e is applied;twhenjn is '3,:the termtrisilane Just asin the hydrocarbons, the hydro-,

- mixture.

poratesilica our llerrinwthe resins -unless purchase-rs,

specify otherwise. 'Unfortunately the Vincorporation of silica flour makes the composition susceptible to penetration vby Water. This penetration appearstobe promotedY f by the water preferentially wetting the silicaflour filler and displacing the epoxy` upward. It is` evident that this condition is highly undesirable. v It has been found that f the addition ,of4 a small but etective amount of'an aminofunctional organosilane or: an organohalosilane *will` pre-- vent water from penetrating the lepoxy. resin-silica our Preferably, lthe amountV of .organofun'ctlonal silane is'between .05% and 10% by welght of resin.Y

A silane is a direct counterpart of a hydrocarbon having silicon instead of rcarboni atoms `The genericI formula vfor a silaneis (Sini-ign@ ascornpared with CIIHM1 2' lfor a corresponding hydrocarbon; Whenn is 1, (wifi-espendirig to methane, a compound is usuallylcalleda, s-ilane,

rather than. amonosilane. Howevenwhennf'is', the

is applied;` etc.

gen atoms can be substituted byvarious. groups or other When an of the epoxide groups with aryl or alkyl hydroxyls such Y as-V alcohols (KOH), with alcohols rkand tertiary amines (ROH-i-RgN) or Ywith di- `or trihydric phenols Ar(OH)2 or Ar(OH)3; and (3) cross linkage with curingage'nts such'las polyfunctional primary or secondary amines.' (ROH) (NHglf-or (ROHMUJH),V with dibasic acids orl the sense used here, R indicates an is an aryl.y group.

vvThere are many amines, dibasic'acids and acid anhydrides that will serve as curing agents. Diethylene triamine, diethylamino. propylamine',"ethylene diamine, trialkyl group and Ar ethylene triamine, tridimethylaminomethylphenol,ibeniyldirnethylamine, metaphenylenediamine, and {LAV-methyl- 1 ene' `dianiiine, are typical -of the amine curing lagents for Vepoxy resins; The acid anhydrides suitable for this purpose are illustratedbyoxalic anhydridephthalic anhydride, pyromellitic dianhydride and dodecenyl succinic anhydride. A preferred curing agentrfor use up to 160 F. is Z-ethyl hexoic acid saltof t'rimethylarninornethylphenol, in a concentration rangek ofv6% to 16% by weight.`

Alpreferred curing agent for use in the range of temperaf whiiethe .dump bauer inustraied'in rio. 1 is particularly suitable for use with the invention, -itis apparent that i other-.types of dump bailers may housed.V Forexarnple, vunder certain circumstancesit may be desirable tofsepaf rate the aluminumA balls fromthe thermosetting resinf In thiscase'fa second explosive plug may be incorporated Within thel baler and may be separately detonated by'electrical'energy'from the'earths surface jso` that the I-resin-hardener**mixture Vmay be A,deposited separately from :the'ballsl f `Under many. circumstances it isV necessary Vand desirable to incorporatea quantity of a filler `such as sili'callour in the Vepoxy resin; for ,the purpose of controlling the exotherm vdevelopedby`theresin-hardener mixture while it is setting, andfor increasing the-density of jtlemixture. l\/ianufac-'V turers of epoxy resins li'avefmade it: apractiee to' .'incorf 'tures from 160` F. to 25.0? F. is 30%' by weight ofV di Y amino-diphenyl-Sulfne a1011g1with1ro's% of bomma-z uoride monoethylamine.

'. In the same manner. as described'-intheaboveexample,`V `the ethoxygroup, the'ethyl'eneoxide group, or the propyl-f erieoxi'dev group canv besubstitut'ed forfthe trimethoxy -portion of-the molecule. i Similarly, ,the aminomethyl atoms. -Thus, a monosilane type' of .organosilane may be designated by the general formulae: RSiH3,`,l {2SiH2,' RBSiH, and R4Si where the substituting groups designated L 'R may be alkyl,V alkoxy,` aminoalkyl, Vor elkeneoxide groups.' In general, the substitutingfgroups on'thesilieonr atom willbe la mixture of alkyoxy and` alkyleneoxidev groups, to promote Water solubility,'along,Withalkyl andl aminoalkyl. groups to promote `activity withthev resin to give the'firm bond betweenthe resin and ,tltlecasirigv To4 avoid ,steric hindrance' effects, it isr'desirablei to' keepthe molecular weightV of theV substituting 4groups low; therefore, the substituting groupsshou'ld have less than 4 carbon atoms thereinx:

'Amino-functional organosilanes (having vlejss than 4 gsili- Y `C0111` atoms, and organohalosilanes `are preferred.` lfhe preferred' aminofunctional silane is Z-aminoethyl ammo` propyl trimethoxy silanewhich is represented by the y amiuoethyl aminoethyl, `andi l-a'minopropyl aminoethyi.

to form satisfactory lcompounds for usein thepresent int rventioni(` An example of an aminofunctio'nalldisil'ane typeV f 0fk Organosilane that also ,mayV -be used is l-'trimethoxy group,v theffZ-aminoethyl group,V or the Z-jarnirlopropylvv groups could be used, as well as. could an 'aminornethyl, v VVaminoethyl, `or aminopr'opylY-group'substituted on` the* second ca'rbonatom othejaminopropyl `group. "f1 n Also suitabley for;use y:are 4the yorganohalosilanes illustrated fby1 the ,'generic 5 formulaew RSiCla, RzSiClz, ,and l3SiClr In this type of1compund,the substituting'"groupsdesignated ,R. are-alkyl grOuPsfand Lwhen more" than one end of the dump bailer.

sil-ane, chlorotrimethylsilane, trichlorophenylsilane, trichlorocyclohexylsilane, trichlorovinylsilane and dichlorodiphenylsilane. From the above it can be seen that organohalosilanes may be used where the alkyl group has between l and 16 carbon atoms therein. In general, compounds having alkyl groups with low molecular weights are preferred because they offer less steric hindranceto the interaction with the .resin to generate a firmer bond between the casing and the resin to enhance their utility in preventing water-wetness.' Y

With reference now to FIGS. 2 and 3, lthere is shown in each figure a typical well installation including a borehole 13 penetrating an upper productive earth formation 23 having its lower endpacked off to the casing by adeposited on top of the supportY plug, the dump bailer may be retracted up the tubing as illustrated in FIG. 3.

The resin-hardener mixture should be allowed to set for at least 2 hours after deposition thereof in the well casing. The length of time required for setting of the mixture is determined by the amount of catalyst per unit volume of resin incorporated in the mixture and by the ambient well temperature at the depth of the plug. In

many instances it may be desirable to allow the plug to a set undisturbed for as long as 24 or 48 hoursto insure complete hardening ofv the cementitious mixture. Thereafter, production may be initiated from formation 15 by perforating the casing at the level of upper formation 15 so as to open fluid communication between the earth formation 15 and the interior of the casing so that the formation may be produced.

It has been found that bridge plugs formed in the manner described above are more than three times as strong as a cement plug of equivalent surface area in adherence with the interior of the-casing. The reason that the plug formed in the manner described above is strong relative well packer v25. The casing is shownas having been perforated by a-perforating gun orother apparatus to produce f a plurality of perforations 27 for the purpose `of opening bore ofcasing stringV y19.V To this end a ithrough-"tubing stop device 29'is run through the tubing 23from the earths surfaceand isset in :the casing between the formations 15 and 17.-r A particularly desirable stop device includes a metal petal basket'31 which is expansible to the inner surface of the casing string 19. A quantity of pea gravel and sand 33 is' dumped on the stop device 29 and is retained abovethe/ deviceby the metal' petal basket V31. Preferably, the pea gravel and sand isdeposited so that the bottom portion is almost entirely of pea gravel,

the top portion is almostentirely of'sand,k and graduated percentages .of Vpea gravel and sand are therebetween. The combination of the stop device 29 and the pea gravel and sand 33 may be termed a support plug.

At the earths surface the dump bailer is filled'lwith th desiredquantity of resin-hardener mixture and metal balls. Preferably, the Ametal balls are'suflicient in quantity so that when the resin-hardener mixture and the balls vare deposited on top of the pea graveland sand 33, the metal balls will pack above the support plug and will extend from the vpea gravel and sand tothe topof the resinhardener mixture. The'dump bailer is lowered through the tubing 23 until it is slightly above the upper surface' of the pea gravel and sand 33. The explosive plug 5 is detonated so that the epoxy resin will flow from the lower Preferably, the dump bailer is maintained at its initial position for a substantial period of time until as much as possible of the liquid resin-hardener mixture has owed therefrom. The dump bailer then is very slowly pulled upwardly so as to keep the` lower open endy thereof (or discharge port) `below the` surface of .the liquid insofar as possible, thuspermitting This tity of resin-hardener mixture and the balls have been dealof heat must be dissipated if the temperature of the mixture is not to rise excessively. When the resin-hard-v ener mixture sets rapidly at a temperature much higher than its environmenn'it will shrink on coolingtoisuch a degree that it will at least partially separate fromfth'e casing, particular-ly when the casing has a diameter greater f than about 3 inches. However, when metal balls are in-V cluded in the mixture, a large portion of the generated heat will be absorbed byV theballs so that the mixturel will not rise to an extremely high temperature.l This does not completely explain thev magnitudefof success obtained by the method, but it is atleast a partial explana tion thereof. y Y y Y ,l The desirability ofvdepositing the resin-,hardener mixture by keeping the deposition port below the upper surface of the mixture insofaras possible has been experimentally established.. It is believed that, as. they resin lls the casing displacing water upwardly, the resin preferen-v tially wets the casing and wipes away any water previously wetting, the pipe. It has been established that. whenI the resin-hardener mixture is simplydumped through water to the support plug, a water Y'film' is trapped between the water and the interior of the casing, thusadecreasing v the area -of Acontact between the resin-hardener lmixture andthe casing. The desirability of kdepositing thefresinhardenermixture'in thernanner described was established by the following'experiment. T wo sets of test pipe nipples were lled with saturated salt water. InIthe first set the' epoxy resin-hardener mixture was deposited inthe bot-Y toms of the pipes with a bukrette, the opening o f which remained below the surface of the lquidmass. vIn the second set of 'pipe nipples the liquid mixture was dropped through the salt water and allowed to settle to the bottom. Enough vresin-hardener mixture was'placed in each of the'p'ipes to form a plug 11/2 inches long.'A The samples were tested-after curing for24 hours at 150 F. bydetermining the hydraulic pressure required to extrude the plugs from the nipples. The samples which were droppedv through the Water failed at an average pressure of 350 'p.s.i., while those deposited in the manner described above failed at an average pressure of 2470 p.s.i.

The desirability of including an organo-functional silane when silica our filler is incorporated in the mixture was a demonstrated in the following manner. Epoxy mixtures containing .O05 gram each of a multiplicity of waterrepellingagents per Vgram of epoxy resin were poured into test tubes to a depth of about 1% inches. Salt water was then pouredinto each of the test tubes above the resin and the `resin was allowed to cure at F. After curing.'

, the depthY of. water invasion :into each of the samples was measured. The results'fof these tests are tabulated below.

. Y The Dow-Corning Z-6020 listed in the .table is Z-aminoethyl aminopropyl trimethoxy silane. Y

' Depth of Humble Corexit Y a f Y 11/8 To study the amount of the exotherrn and to' study its experiments was done in 51/2 inch casing Vto more nearly simulate actual weil conditions. Inthese experiments V1- foot plugs of epoxy resin were poured into the 51/2 inch casing and held in a bath at 150Y F. Inhalt these plugs,

one inch aluminum spheres were used to ll the resiri,1and

in the 'ntherhalf'y there were no aluminum spheres. fDuringthe curing period of 24 khours itu/astound, by v using thermocouples in the resinmass, that when no aluminum. spheres were included the exothermic nature of the polym.

' erization caused the temperature to rise to above 212 F.

In contrast', those plugs that contained the aluminum spheres rheated only toV 170 F. Afterthe heat from the z reaction wasdissipated into the bath and the plugscooledy to 150 F., it was'ound that one that had heated to above 2127 F. had contracted away fromthe pipe and allowed i water to flow freely past the plug. v The plugs -that con.-

tained the aluminum spheres sustaineda pressure difierentialoff-SS-O-lOOO p.s.i..before failure. This pressure at failure is contrasted with 181)#275` p.s.i. `for portland' cement,-the material-normally used `in'plugback operations in wells.

effect on the bonding of theresin to the pipe, a group of 2. A method of plugging thebore of awell pipe having 1 a support plug secured therein at a predetermined level, comprising: I

forming a `liquid mixture of a thermosetting phenolic condensation resin and a-catalytic hardener therefor; depositing saidliquid mixture on saidv support plug along with a pluralityV of. metal balls sufficient in number to be .interspersed throughout said Vliquid mixture to the surface thereof; and` delayingproduction of the well untilsaidthermosetting 'condensation resin has hardened. l3. A method of plugging-the bore of a Well pipe having a support plugsecured at a'predeterrnined level therein using an elongated Ldump bailer having a ydiameter lessY l than lthe well pipe and having anv ejection portfor liquid containedV therein, comprising: with said dump bailer, depositing onsaid support plug `arnixture of a normally liquid Iepoxy resin,-a catalytic hardening agent therefor, and aiplurality of metal balls havingan Voutside diameter not less Vthan half the inner diameter ofV the -dump bailer and suicient in numberfto be interspersed through the epoxy resin Y and hardener mixture to .theV vsurface thereof;` andv delaying productionfofithe well until said liquid epoxy resin has hardenedfjf Y. y i

4. vAr'method of plugging the bore oa wellV pipehaving a support plugsecured at a predetermined level therein i using `an elongateddump bailer havingadiameter less 3 KVThe invention is not necessarily to be restricted to `the i 'sequence .of steps, spec'ic structural details, or arrange- .ment lof partswh'erein set fortli' as various modications thereof` may be effectedwithoutfdepartingfrom the spirit l j and scope of this inventiongf Thefobje'cts andfeaturesof `theinvention havingbeen completely described, "what we .wish to claimA is:

, v1. A method ofpluggingthe bore ofa welljgiipeV having a support plug secured therein at a predetermined level, comprising:

tharrthe Vwell'pipeva'nd having an ejectionport forliquid contained therein, comprising:Y Y

. with saiddump bailer, depositingon saidr support plug agmlxture. of a `thermosetting .phenolie'resin anda `v catalytic hardeningl agent therefor'while insofar asA belowthe upper surface'of the deposited mixture;l

interspersing a pluralityof metal balls in theY deposited mixture `suflicientin. 'number'to be interspersed Vthrough"themixtureto' the surfacethereof;V and ldelaying production ofthewell'until thefthermosetti'ng `phenolic resin has hardened; f 5.v The methodjof claimA wherein the metal balls are f carried withinthedurnpbailerand have an outside diamf eter not` less than half the, inner diameter of thejdump v depositing on said `supportjplug a quantity. of a liquid:

mixture of -a' thermosetting phenolic condensation resin and afcatalytichardener therefor, and' a.plu, rality of metallic balls sutiicient in ,number vto be ,interspersed through said mixturey tothe surfaceV thereof;. and 1 Y -,delaying production of the gwell until said thermosetting phenolic condensation. resin has'hardened. Y

OTHER VvRarinfiaiflcissf, `R Scott,= Robert W.: ffHowThrough-Tubing YBridge Plugs WorhWorld Oil, October, 1959, pp. k141 tof149frelied on.

possible keeping the ejection port of thedump bailer 

1. A METHOD OF PLUGGING THE BORE OF A WELL PIPE HAVING A SUPPORT PLUG SECURED THEREIN AT A PREDETERMINED LEVEL, COMPRISING: DEPOSITING ON SAID SUPPORT PLUG A QUANTITY OF A LIQUID MIXTURE OF A TERMOSETTING PHENOLIC CONDENSATION RESIN AND A CATALYTIC HARDENER THEREFOR, AND A PLURALITY OF METALLIC BALLS SUFFICIENT IN NUMBER TO BE INTERSPERSED THROUGH SAID MIXTURE TO THE SURFACE THEREOF; AND DELAYING PRODUCTION OF THE WELL UNTIL SAID THERMOSETTING PHENOLIC CONDENSATION RESIN HAS HARDENED. 